Light Emitting Diodes (LEDs) are one type of solid-state light generating devices that have found their way in lighting applications, display applications, photo-therapeutic applications, and other applications where a compact, low voltage, rugged, and high efficiency light source is advantageous. In many such applications, a number of LEDs are arranged into an array or other pre-determined arrangement having similar or dissimilar LED types.
In display applications, LEDs emitting in the red, green, and blue colors are closely packed to form a color “pixel” that blends the three colors. In this manner white light can be generated. Alternatively, by selectively varying the optical output intensity of the three colored LEDs, a selected color can be generated. An array of such “pixels” can form a color display or an illuminating surface emitting white light. In lighting or photo-therapeutic applications, an illumination unit or panel containing LEDs arranged in an array can be formed.
The LEDs can also emit only red, blue or green color, not from the combination of the red, green and blue dies as stated above, but having the individual dies on the package itself emitting the different specific colors.
However, several hurdles remain in the use of LEDs in those applications. One problem associated with the prior LED illumination panel or display is its thickness. This means that the unit must be of the appropriate thickness. For example, a relatively thick LED illumination unit typically affects the therapeutic effectiveness of the unit due to reduced optical intensity. On the other hand, patient safety and comfort may be adversely affected if the unit is made too thin.
The other problem is the rigidity (i.e., not flexible to be bent) of the prior LED illumination unit. As is known, many of the above mentioned applications require that the illumination unit to be flexible. For example, in the lighting application where the LED illumination unit is used as a vehicle lamp, the illumination unit needs to be flexible or soft enough to form a desired shape or contour to follow the contour of a vehicle lamp. In the photo-therapeutic applications, the unit must be flexible enough so that it can follow the contour of the human body part in order to provide safe but effective phototherapy to that body part.
Therefore, what is needed is a thin, flexible, and safe illumination unit.